1. FIELD OF INVENTION:
The present invention relates to offshore seismic surveying.
2. DESCRIPTION OF THE PRIOR ART:
In offshore seismic surveying, particularly in areas near river deltas, portions of the data obtained are often of very low quality. These low quality data typically range from "non-useable" data, termed NU data in the art, where the survey data obtained are not useable for analysis, to "no record" data, known as NR data, where no meaningful seismic data are obtained. One of the main reasons for this phenomenon is that river delta regions typically contain massive deposits of unconsolidated, recent sediments from the river, with the sediments usually containing gas-filled vesicles. Certain of these gassy sediment regions, known as scar zones, form a virtually acoustically opaque layer to reflection seismic surveying, precluding meaningful surveying and analysis of seismic data for regions which are likely to be of interest in locating hydrocarbon deposits.